Security incident · 2021-09-29
Compound V2
According to the public DefiLlama incident dataset, Compound V2 (Ethereum) suffered a security incident on 2021-09-29, with about $147.0M reported lost.
| Date | 2021-09-29 |
|---|---|
| Reported loss | $147.0M |
| Chain | Ethereum |
| Target type | DeFi Protocol |
| Technique class | Token & Share Accounting |
| Technique | Arithmetic Error |
| Bridge incident | No |
| Within 2021 | #3 by loss that year, 5.1% of all reported losses that year |
How this kind of attack works
The contract's bookkeeping was wrong, for example the conversion between shares and assets, so the attacker redeemed far more than they put in.
Would a pre-payment check have helped
Accounting and share-math bugs are contract-layer problems for code audits.
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